Business research methods

A survey was sent to a simple random sample of college sophomores. The sample size was 200. When asked whether or not they liked Frank Sinatra's music, 40 of these students did not give any answer. This is an example of A) a stratified sample. D) the margin of error. B) a census. E) nonresponse. C) bias.

E

An example of a categorical variable is the A) number of songs on my MP3 player. B) title of a song on my MP3 player. C) duration of a song (in seconds) on my MP3 player. D) composer of a song on my MP3 player. E) Both B and D are correct.

E

Question 11. Which of the following is a source of nonsampling error in a sample survey? A) Voluntary response sampling B) Using voter registration lists as the sampling frame C) Variation due to chance in choosing a sample at random D) Using 95% confidence E) None of the above

E

Question 3. The essential difference between an experiment and an observational study is that A) observational studies always involve large numbers of subjects, but experiments never do. B) in an experiment, information is gathered only on animals or things, but in an observational study, only information about people is gathered. C) an observational study imposes treatments on the subjects, but an experiment does not. D) observational studies cannot have variables. E) an experiment imposes treatments on the subjects, but an observational study does not

E

Which of the following statements do you think could possibly be true? A) The number of students enrolled at City College decreased by 103.4% last year. B) A basketball team took 20 free throws in a game last week and made 72.6% of them. C) Yesterday, it was 30 ° (Fahrenheit) in Chicago. Today, it warmed up to 60 ° . This is a 50% increase in the temperature. D) My weight decreased by 10% last year but then increased by 10% in the first two months of this year. Thus, my overall weight from the beginning of last year until now is unchanged. E) None of the above

E

are the objects described by a set of data. Individuals may be people, but they may also be animals or things.

Individuals

is a variable that has an important effect on the relationship among the variables in a study but is not one of the explanatory variables studied

Lurking

are errors not related to the act of selecting a sample from the population. They can be present even in a census.

Nonsampling errors

use impersonal chance to assign subjects to treatments so treatment groups are similar, on average

Randomize

are errors caused by the act of taking a sample. They cause sample results to be different from the results of a census.

Sampling errors

what graph is used for length and IQ

Scatterplot because it is quantitative

What the Margin of Error Doesn't Say

The announced margin of error for a sample survey covers only random sampling error. Undercoverage, nonresponse, and other practical difficulties can cause large bias that is not covered by the margin of error.

what graph is used for brand type of you phones

bargraph because its categories

what graph is used for length of women and length of men

boxplot

is a sample survey that attempts to include the entire population in the sample.

census

Two variables are_______ when their effects on a response variable cannot be distinguished from each other. The confounded variables may be either explanatory variables or lurking variables.

confounded

the effects of lurking variables on the response by ensuring all subjects are affected similarly by these lurking variables. Then simply compare two or more treatments

contro;

Selection of whichever individuals are easiest to reach is called

convenience sampling

deliberately imposes some treatment on individuals to measure their responses. The purpose is to study whether the treatment causes a change in the response.

experiment

is a variable that we think explains or causes changes in the response.

explanatory variable

what graph is used for salaries of professors

histogram

what graph is used for length of people since 1500

line graph- CHANGE OVER TIME

A confidence statement has two parts: a __________ and a ___________

margin of error/level of confidence

observes individuals and measures variables of interest but does not attempt to influence the responses.

observational study

is a number that describes a population. A parameter is a fixed number, but in practice we don't know the actual value of this number

parameter

is a dummy treatment with no active ingredients. Many patients respond favorably to any treatment, even a _________. This response to a dummy treatment is the ______

placebo

in a statistical study is the entire group of individuals about which we want information

population

is a variable that measures an outcome or result of a study

response

is a variable that measures an outcome or result of a study

response variable

is the part of the population from which we actually collect information. We use information from a sample to draw conclusions about the entire population

sample

is a number that describes a sample. The value of a statistic is known when we have taken a sample, but it can change from sample to sample. We often use a statistic to estimate an unknown parameter

statistic

An observed effect of a size that would rarely occur by chance is called

statistically significant

Divide the sampling frame into district groups of individuals, called _______ . Choose the _______ according to any special interest you have in certain groups within the population or because the individuals in each stratum resemble each other. Step 2: Take a separate SRS in each stratum and combine these to make up the complete sample.

stratified random sample

is a long string of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 with these two properties: 1. Each entry in the table is equally likely to be any of the 10 digits 0 through 9. 2. The entries are independent of each other. That is, knowledge of one part of the table gives no information about any other part

table of random digits

is any characteristic of an individual. A variable can take different values for different individuals.

variable

chooses itself by responding to a general appeal. Write-in or call-in opinion polls are examples of voluntary response samples

voluntary response sample

Convenience samples and voluntary response samples are often biased

...

An important reason for the use of randomization in designing experiments is that it tends to A) reduce confounding. C) eliminate response error. B) allow double-blinding. D) reduce the placebo effect

A

Question 17. Medical experiments, such as one to compare aspirin with a placebo, are often double-blind. This means that A) neither the subject nor the doctors know which treatment the patient received. B) subjects choose which treatment they get, but do not tell the doctors. C) the doctors choose which treatment to give each subject, but do not tell the subjects. D) subjects are not told either their treatment or their medical condition

A

Sale of eggs that are contaminated with salmonella can cause food poisoning among consumers. A large egg producer takes an SRS of 200 eggs from all the eggs shipped in one day. The laboratory reports that 9 of these eggs had salmonella contamination. Unknown to the producer, 0.1% (one-tenth of one percent) of all eggs shipped had salmonella. Question 8. In the situation above, A) 0.1% is a parameter and 9 is a statistic. B) 9 is a parameter and 0.1% is a statistic. C) both 0.1% and 9 are parameters. D) both 0.1% and 9 are statistics. E) 0.1% is an estimate and 9 is a margin of error

A

To illustrate a talk you are giving, you want to make a graph to compare the consumption (in gallons) of alcohol per person for several countries. For example, this is 2.87 gallons per person in France and 1.74 gallons per person in the United States. You should make a

A

We are 95% confident that the value of a parameter is between 48% and 52% points. If we want to be 99% confident, the range of points would be A) wider because higher confidence requires a larger margin of error. B) narrower because higher confidence requires a smaller margin of error. C) wider because higher confidence requires a smaller margin of error. D) narrower because higher confidence requires a larger margin of error.

A

f a sampling method is biased, then A) we need to improve the sampling method to remove the bias. B) we need to increase the sample size to remove the bias. C) we should sample from a larger population. D) the sample statistic will be close to the population parameter. E) the center of the distribution of the statistic will be close to the population parameter

A

A recent survey of 35,101 randomly selected U.S. adults studied the religious affiliation of Americans. The sample for this survey is: A)religious affiliation. B) the 35,101 people questioned. C) all adults with telephones. D) all U.S. adults.

B

Confounding often defeats attempts to show that one variable causes changes in another variable. Confounding means that A) this was an observational study, so cause and effect conclusions are not possible. B) the effects of several variables are mixed up, so we cannot say which is causing the response. C) we don't know which is the response variable and which is the explanatory variable. D) we would get widely varied results if we repeated the study many times.

B

In a(n) _____________, the environments of the subjects are controlled or manipulated by the researcher. A) census B) experiment C) observational study D) sample survey

B

In order to be correct, a line graph of the number of suicides per year in the United States must have A) number of suicides on the horizontal scale. B) years on the horizontal scale. C) either suicides or years on the horizontal scale, as long as equal intervals are used. D) bars of equal width.

B

Question 12. Scotland is considering independence from England. An opinion poll showed that 51% of Scots favor independence. Another poll taken at the same time showed that only 34% favored being separate from England. The primary reason these results differ by so much is that A) samples will usually differ just by chance due to random sampling. B) the wording of questions has a big effect on poll results. C) more follow-up efforts reduced the nonresponse rate of the second poll. D) the sample sizes are different, so the margins of error are different

B

Question 14. The explanatory variable in this study is A) whether the subject had an auto accident. B) whether the subject was using a cell phone. C) the risk of an accident. D) whether the subject owned a cell phone.

B

Question 7. If we take many simple random samples from the same population, we expect A) the same values of the statistic for each sample. B) the values of the statistic will vary from sample to sample. C) a different value of the parameter for each sample. D) a problem with voluntary response. E) a problem with bias.

B

Some common sources of nonsampling error in samples of human populations are A)using voluntary response samples; some subjects lie. B) some subjects lie; some subjects can't be contacted. C)some subjects can't be contacted; drawing a sample from names in a telephone directory. D)Both B and C are correct. E)Answers A, B, and C are correct.

B

Voluntary response polls almost always suffer from A) low bias. B) high bias. C) no bias. D) randomization.

B

You want to make a graph to display the distribution of the salaries of the 1500 professors at a very large university. The best choice is a A) boxplot. D) pie chart. B) histogram. E) stemplot . C) line graph

B

A poll questioned 1025 women and 472 men. The design of the sample chose separate samples of men and women and planned to interview more women than men. This is a A) systematic random sample. C) stratified random sample. B) census. D) simple random sample.

C

An observed effect that is of a size that would rarely occur by chance is called A) a randomized effect. B) the confounding effect. C) a statistically significant effect. D) the placebo effect.

C

Below is a stemplot of the scores on a recent statistics test. (Key: 8|2 = 82%) 4 | 9 5 | 26 6 | 069 7 | 367788999 8 | 258 9 | 55 10| 0 The overall shape of this distribution is A) clearly skewed to the right. C) roughly symmetric. B) clearly skewed to the left. D) without a clear shape.

C

Question 10. We divide the class into two groups: first-year students and others. We then take random samples from each group. This is an example of

C

Question 15. An example of a lurking variable that might affect the results of this study is A) whether the subject had an auto accident. B) whether the subject was using a cell phone. C) whether the subject was talking to a passenger in the car. D) whether the subject owned a cell phone

C

Question 16. A park ranger wants to know if visitors to Shenandoah National Park can properly identify poison ivy. She shows several plant varieties to 117 randomly selected visitors one week, and 74 of them correctly identify the poison ivy. The biggest potential weakness of experiments is that A) experiments do not give good evidence for cause and effect. B) experiments only work when we can give a placebo. C) it can be hard to generalize conclusions beyond the actual subjects to a wider population. D) informed consent is often not possible

C

Question 6. Which of these statements about a table of random digits is true? A) No two-digit number appears more than once in a given row. B) It is not possible for 00000 (five zeros in a row) to appear in the table. C) It is possible for five consecutive digits (e.g., 12345) to appear in the table. D) All of these are true. E) None of these is true.

C

A student reports that, of a simple random sample of 50 college undergraduate students, 21% were taking more than fifteen credit hours. We know that the student has made a mistake. Why? A) The sample contains 50 students, so percentages should be multiples of 2%. B) The sample contains 50 students, so percentages should be multiples of 0.02% C) 21% of 50 students is 10.5 students, and you cannot sample a fraction of a student. D) Both A and C are correct. E) Both B and C are correct.

D

A well-drawn histogram should have A) bars that are all the same width. B) no space between bars (unless a class has no observations). C) a clearly marked vertical scale. D) All of the above

D

For a sample to be a simple random sample of size n A) the variability must be small. B)n must be a large number. C) every item in the population must be selected. D) every collection of n individuals must have the same chance to be the sample actually chosen. E) the size of the population must be smaller than n

D

If the mean of a list of numbers is 12.4, and the standard deviation is zero, you know that A) you have made an arithmetic mistake. B) the median is 12.4. C) all the numbers in the list are 12.4. D) Both B and C are correct.

D

To reduce the variability of estimates from an SRS, you should: A) use a smaller sample. D) use a larger sample. B) increase the bias. E) use a percent, not a count. C) use a count, not a percent.

D

Use the following to answer Questions 13-15: Does using a cell phone while driving make an accident more likely? Researchers compared telephone company and police records to find 699 people who had cell phones and were also involved in an auto accident. Using phone billing records, they compared cell phone use in the period of the accident with cell phone use the same period on a previous day. Result: The risk of an accident was four times higher when using a cell phone. Question 13. This study is a(n) A) randomized comparative experiment. B) experiment, but without randomization. C) simple random sample. D) observational study, but not a simple random sample

D

You measure the age (years), weight (pounds), and marital status (single, married, divorced, or widowed) of 1400 women. How many variables did you measure? A) 1400 B) One C) Two D) Three E) 1403

D

he average wage of production workers (adjusted for the effects of inflation) was $11.08 an hour in 1981 and $10.35 an hour in 1991. In the decade of the 1980s, wages went down by about

D